User:Alondra Vega/Notebook/Research/2010/02/16

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What I did today

  • We began by working with the worksheet that we made last week and named it logFC. In this worksheet we computed the log base 2 of each value in the data. (note:FC means full change) The command/formula used in excel is =LOG(B2,2).
  • Then we made a new worksheet to normalize the data from the previous worksheet (logFC). This worksheet we named normalized. We added two rows to calculate the average and the standard deviation of each value. The average formula is =AVERAGE(B3:B6423). It shows that we took the average of all the genes at a specific time. The standard deviation formula is =STDEV(B4:B6423). It shows that we took the standard deviation of each gene at an specific time. Then we added a column to calculate the difference between the log value and the average value divided by the standard deviation. the formula look like =(B4-B$2)/B$3. (Note: B4 is the log value, B$2 is the average value and B$3 is the standard deviation value. The dollar sign is to hold the place value of 2 while the column B is interchangeable.)
  • Then we made a new worksheet and copied the previous sheet (with paste special to only paste values not formulas) and only kept the normalized columns calculated previously. This worksheet is called average and p-value. To calculate the average we used the formula =AVERAGE(B2:D2). We also calculate a T statistic that tells us whether the scaled and centered average log ratio is significantly different than itself. We used a modified formula =AVERAGE(N2:P2)/(STDEV(N2:P2)/SQRT(number of replicates)). We also calculated a p-value with the equation =TDIST(ABS(R2),degrees of freedom,2). The degress of freedom is n-1.
  • We finally copied this information into a new worksheet called final. This will help us view the information in an organized manner.



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